1. Field of the Invention
The invention relates to a zoom lens having a compact structure and a high zoom magnification ratio.
2. Description of the Related Art
Recently, use of optical imaging devices, such as digital still cameras or digital camcorders, including a solid-state imaging device such as a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS), each of which converts an optical image into an electrical signal, is rapidly increasing.
Thus, imaging devices having high resolution are needed. In response to such a need, imaging lenses having excellent imaging functions, in particular, zoom lenses having excellent imaging functions, are also needed. In addition, characteristics such as a wide viewing angle, portability, and a high zoom magnification ratio of 10 or more are also required for imaging devices. Thus, a variety of compact and lightweight imaging devices having high performance are being developed.
As such a zoom lens, for example, a zoom lens including first through fourth lens groups respectively having positive, negative, positive, and positive refractive powers sequentially disposed from an object side, is generally used, and optical structures that embody high zoom magnification ratios and aberration of which is easily corrected are getting more attention.